Modified bubble level senses pitch and roll angles over wide range

Bubble level sensor with fiber-optic field flattener is simple, rugged, small, and impervious to temperature and vibration effects. Pitch angles from -15 deg to +40 deg and roll angles of +30 deg are determined within 0.5 deg

Earth-like sand fluxes on Mars

Strong and sustained winds on Mars have been considered rare, on the basis of surface meteorology measurements and global circulation models, raising the question of whether the abundant dunes and evidence for wind erosion seen on the planet are a current process. Recent studies showed sand activity, but could not determine whether entire dunes were moving—implying large sand fluxes—or whether more localized and surficial changes had occurred. Here we present measurements of the migration rate of sand ripples and dune lee fronts at the Nili Patera dune field. We show that the dunes are near steady state, with their entire volumes composed of mobile sand. The dunes have unexpectedly high sand fluxes, similar, for example, to those in Victoria Valley, Antarctica, implying that rates of landscape modification on Mars and Earth are similar

Possible X-ray diagnostic for jet/disk dominance in Type 1 AGN

Using Rossi X-ray Timing Explorer Seyfert 1 and 1.2 data spanning 9 years, we study correlations between X-ray spectral features. The sample consists of 350 time-resolved spectra from 12 Seyfert 1 and 1.2 galaxies. Each spectrum is fitted to a model with an intrinsic powerlaw X-ray spectrum produced close to the central black hole that is reprocessed and absorbed by material around the black hole. To test the robustness of our results, we performed Monte Carlo simulations of the spectral sample. We find a complex relationship between the iron line equivalent width (EW) and the underlying power law index (Gamma). The data reveal a correlation between Gamma and EW which turns over at Gamma <~ 2, but finds a weak anti-correlation for steeper photon indices. We propose that this relationship is driven by dilution of a disk spectrum (which includes the narrow iron line) by a beamed jet component and, hence, could be used as a diagnostic of jet-dominance. In addition, our sample shows a strong correlation between the reflection fraction (R) and Gamma, but we find that it is likely the result of modeling degeneracies. We also see the X-ray Baldwin effect (an anti-correlation between the 2-10 keV X-ray luminosity and EW) for the sample as a whole, but not for the individual galaxies and galaxy types.Comment: Accepted for publication in ApJ, 14 page

Molecular Control of the Amount, Subcellular Location and Activity State of Translation Elongation Factor 2 (eEF-2) in Neurons Experiencing Stress

Eukaryotic elongation factor 2 (eEF-2) is an important regulator of the protein translation machinery wherein it controls the movement of the ribosome along the mRNA. The activity of eEF-2 is regulated by changes in cellular energy status and nutrient availability, and posttranslational modifications such as phosphorylation and mono-ADP-ribosylation. However, the mechanisms regulating protein translation under conditions of cellular stress in neurons are unknown. Here we show that when rat hippocampal neurons experience oxidative stress (lipid peroxidation induced by exposure to cumene hydroperoxide; CH), eEF-2 is hyperphosphorylated and ribosylated resulting in reduced translational activity. The degradation of eEF-2 requires calpain proteolytic activity and is accompanied by accumulation of eEF-2 in the nuclear compartment. The subcellular localization of both native and phosphorylated forms of eEF-2 is influenced by CRM1 and 14.3.3, respectively. In hippocampal neurons p53 interacts with non-phosphorylated (active) eEF-2, but not with its phosphorylated form. The p53 – eEF-2 complexes are present in cytoplasm and nucleus, and their abundance increases when neurons experience oxidative stress. The nuclear localization of active eEF-2 depends upon its interaction with p53, as cells lacking p53 contain less active eEF-2 in the nuclear compartment. Overexpression of eEF-2 in hippocampal neurons results in increased nuclear levels of eEF-2, and decreased cell death following exposure to CH. Our results reveal novel molecular mechanisms controlling the differential subcellular localization and activity state of eEF-2 that may influence the survival status of neurons during periods of elevated oxidative stress.España, Ministerio de Ciencia e Innovación BFU2010-20882.España, Ministerio de Educación, Cultura y Deporte postdoctoral fellowship (EX2009-0918

Magnetic Properties of Epitaxial and Polycrystalline Fe/Si Multilayers

Fe/Si multilayers with antiferromagnetic interlayer coupling have been grown via ion-beam sputtering on both glass and single-crystal substrates. High-angle x-ray diffraction measurements show that both sets of films have narrow Fe peaks, implying a large crystallite size and crystalline iron silicide spacer layers. Low-angle x-ray diffraction measurements show that films grown on glass have rougher interfaces than those grown on single-crystal substrates. The multilayers grown on glass have a larger remanent magnetization than the multilayers grown on single-crystal substrates. The observation of magnetocrystalline anisotropy in hysteresis loops and $(hkl)$ peaks in x-ray diffraction demonstrates that the films grown on MgO and Ge are epitaxial. The smaller remanent magnetization in Fe/Si multilayers with better layering suggests that the remanence is not an intrinsic property.Comment: 9 pages, RevTex, 4 figures available by fax. Send email to [email protected] for more info. Submitted to '95 MMM proceeding

Publication and patent analysis of European researchers in the field of production technology and manufacturing systems

This paper develops a structured comparison among a sample of European researchers in the field of Production Technology and Manufacturing Systems, on the basis of scientific publications and patents. Researchers are evaluated and compared by a variegated set of indicators concerning (1) the output of individual researchers and (2) that of groups of researchers from the same country. While not claiming to be exhaustive, the results of this preliminary study provide a rough indication of the publishing and patenting activity of researchers in the field of interest, identifying (dis)similarities between different countries. Of particular interest is a proposal for aggregating analysis results by means of maps based on publication and patent indicators. A large amount of empirical data are presented and discusse

Spin-dependent electrical transport in ion-beam sputter deposited Fe-Cr multilayers

The temperature dependence of the electrical resistivity and magnetoresistance of Xe-ion beam sputtered Fe-Cr multilayers has been investigated. The electrical resistivity between 5 and 300 K in the fully ferromagnetic state, obtained by applying a field beyond the saturation field (H_sat) necessary for the antiferromagnetic(AF)-ferromagnetic(FM) field-induced transition, shows evidence of spin-disorder resistivity as in crystalline Fe and an s-d scattering contribution (as in 3d metals and alloys). The sublattice magnetization m(T) in these multilayers has been calculated in terms of the planar and interlayer exchange energies. The additional spin-dependent scattering \Delta \rho (T) = \rho(T,H=0)_AF - \rho(T,H=H_sat)_FM in the AF state over a wide range of temperature is found to be proportional to the sublattice magnetization, both \Delta \rho(T) and m(T) reducing along with the antiferromagnetic fraction. At intermediate fields, the spin-dependent part of the electrical resistivity (\rho_s (T)) fits well to the power law \rho_s (T) = b - cT^\alpha where c is a constant and b and \alpha are functions of H. At low fields \alpha \approx 2 and the intercept b decreases with H much the same way as the decrease of \Delta \rho (T) with T. A phase diagram (T vs. H_sat) is obtained for the field- induced AF to FM transition. Comparisons are made between the present investigation and similar studies using dc magnetron sputtered and molecular beam epitaxy (MBE) grown Fe-Cr multilayers.Comment: 8 pages, 10 figures, to appear in Phys. Rev.

Non-Newtonian fluid flow through three-dimensional disordered porous media

We investigate the flow of various non-Newtonian fluids through three-dimensional disordered porous media by direct numerical simulation of momentum transport and continuity equations. Remarkably, our results for power-law (PL) fluids indicate that the flow, when quantified in terms of a properly modified permeability-like index and Reynolds number, can be successfully described by a single (universal) curve over a broad range of Reynolds conditions and power-law exponents. We also study the flow behavior of Bingham fluids described in terms of the Herschel-Bulkley model. In this case, our simulations reveal that the interplay of ({\it i}) the disordered geometry of the pore space, ({\it ii}) the fluid rheological properties, and ({\it iii}) the inertial effects on the flow is responsible for a substantial enhancement of the macroscopic hydraulic conductance of the system at intermediate Reynolds conditions. This anomalous condition of ``enhanced transport'' represents a novel feature for flow in porous materials.Comment: 5 pages, 5 figures. This article appears also in Physical Review Letters 103 194502 (2009

The efficient low-mass Seyfert MCG-05-23-016

The Seyfert 1.9 galaxy MCG-05-23-016 has been shown to exhibit a complex X-ray spectrum. This source has moderate X-ray luminosity, hosts a comparably low-mass black hole, but accretes at a high Eddington rate, and allows us to study a super massive black hole in an early stage. Three observations of the INTEGRAL satellite simultaneous with pointed Swift/XRT observations performed from December 2006 to June 2007 are used in combination with public data from the INTEGRAL archive to study the variability of the hard X-ray components and to generate a high-quality spectrum from 1 to 150 keV. The AGN shows little variability in the hard X-ray spectrum, with some indication of a variation in the high-energy cut-off energy ranging from 50 keV to >>100 keV, with an electron plasma temperature in the 10 - 90 keV range. The reflection component is not evident and, if present, the reflected fraction can be constrained to R < 0.3 for the combined data set. Comparison to previous observations shows that the reflection component has to be variable. No variability in the UV and optical range is observed on a time scale of 1.5 years. The hard X-ray spectrum of MCG-05-23-016 appears to be stable with the luminosity and underlying power law varying moderately and the optical/UV flux staying constant. The spectral energy distribution appears to be similar to that of Galactic black hole systems, e.g. XTE 1118+480 in the low state. The AGN exhibits a remarkably high Eddington ratio of L(bol)/L(Edd)> 0.8 (or L(bol)/L(Edd) > 0.1, if we consider a higher mass of the central engine) and, at the same time, a low cut-off energy around 70 keV. Objects like MCG-05-23-016 might indicate the early stages of super massive black holes, in which a strong accretion flow feeds the central engine.Comment: 8 pages, 5 figures, accepted for publication in A&

Off-Equilibrium Dynamics in Finite-Dimensional Spin Glass Models

The low temperature dynamics of the two- and three-dimensional Ising spin glass model with Gaussian couplings is investigated via extensive Monte Carlo simulations. We find an algebraic decay of the remanent magnetization. For the autocorrelation function $C(t,t_w)=[]_{av}$ a typical aging scenario with a $t/t_w$ scaling is established. Investigating spatial correlations we find an algebraic growth law $\xi(t_w)\sim t_w^{\alpha(T)}$ of the average domain size. The spatial correlation function $G(r,t_w)=[< S_i(t_w)S_{i+r}(t_w)>^2]_{av}$ scales with $r/\xi(t_w)$. The sensitivity of the correlations in the spin glass phase with respect to temperature changes is examined by calculating a time dependent overlap length. In the two dimensional model we examine domain growth with a new method: First we determine the exact ground states of the various samples (of system sizes up to $100\times 100$) and then we calculate the correlations between this state and the states generated during a Monte Carlo simulation.Comment: 38 pages, RevTeX, 14 postscript figure